To be honest, as a top club I'd stay away from him, especially at the supposed prices.
The media usually describe him as a complete midfielder: Technical brilliance paired with great physique, exceptional work ethic and unprecedented maturity. I think all of this is exaggerated. He's a good dribbler and passer and decently pressing resistent but nowhere near current midfield greats such as Modric, Verratti, Kroos, Thiago, Kimmich or de Bruyne. Which for me means he definitely needs his work ethic to become a great himself - but unfortunately, I'm not too convinced of that either. For all his supposed maturity, he's quite toxic towards his team mates, makes many wrong decisions in a game and lacks tactical discipline on top of it. And maybe worst of all, when he's on the ground because one of his bold tackles didn't succeed or the referee didn't give him the foul, he regularly takes his time and walks back into formation. I literally haven't seen such a thing from a worldclass midfielder to date. It really gives you Messi/Mbappe/Neymar/Cristiano vibes which puts his output into some context.
He won't get this kind of freedom at a top club where he'll be asked to do his job and leave the rest to the players who are fielded to do theirs. Among the elite talents that came through at Dortmund, he's the one I have most reservations about, Dembele aside.